Cooperative C60 Binding to a Porphyrin Tetramer Arranged around a p-Terphenyl Axis in 1:2 Host−Guest Stoichiometry

Porphyrin tetramer 1 was newly designed and synthesized to construct a novel cooperative [60]fullerene (C60) binding system. Compound 1 has a p-terphenyl axis, which is expected to act as a scaffold for a guest-binding information transducer. In toluene, 1 can bind 2 equiv of C60 to produce a 1:2 1/C60 complex with association constants of 5800 M-1 (K 1) and 2000 M-1 (K 2). These values are significantly greater than those for control porphyrin dimers such as 2 and 3.